Xinhua Dai
Yuki Aoi
Yumiko Takebayashi
Liping Yang
Xiaorui Guo
Qiwei Zeng
Hanchuanzhi Yu
Hiroyuki Kasahara
Yunde Zhao
aSection of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093-0116, USA
bRIKEN Center for Sustainable Resource Science, Kanagawa, 230-0045, Japan
cSchool of Life Sciences, Jilin Normal University, Siping, 136000, China
dKey Laboratory of Plant Ecology, Northeast Forestry University, Harbin, 150040, China
eState Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, 400716, China
fInstitute of Global Innovation Research, Tokyo University of Agriculture and Technology, Tokyo, 183-8509, Japan
gDepartment of Bioregulation and Biointeraction, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, 183-8509, Japan
More InformationCorresponding author: E-mail address: yundezhao@ucsd.edu (Yunde Zhao)
Publish Date:2020-03-25
Abstract
Abstract
Indole-3-acetamide (IAM) is the first confirmed auxin biosynthetic intermediate in some plant pathogenic bacteria. Exogenously applied IAM or production of IAM by overexpressing the bacterial iaaM gene in Arabidopsis causes auxin overproduction phenotypes. However, it is still inconclusive whether plants use IAM as a key precursor for auxin biosynthesis. Herein, we reported the isolation IAM HYDROLASE 1 (IAMH1) gene in Arabidopsis from a forward genetic screen for IAM-insensitive mutants that display normal auxin sensitivities. IAMH1 has a close homolog named IAMH2 that is located right next to IAMH1 on chromosome IV in Arabidopsis. We generated iamh1 iamh2 double mutants using our CRISPR/Cas9 gene editing technology. We showed that disruption of theIAMH genes rendered Arabidopsis plants resistant to IAM treatments and also suppressed the iaaM overexpression phenotypes, suggesting that IAMH1 and IAMH2 are the main enzymes responsible for converting IAM into indole-3-acetic acid (IAA) in Arabidopsis. The iamh double mutants did not display obvious developmental defects, indicating that IAM does not play a major role in auxin biosynthesis under normal growth conditions. Our findings provide a solid foundation for clarifying the roles of IAM in auxin biosynthesis and plant development.Keywords: Auxin,
Auxin biosynthesis,
Indole-3-acetamide,
CRISPR,
IAMH1,
IAMH2
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